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feat: Support diff lang fences for HTML #208

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Merged
Ilia Permiashkin (p3rmiashkin) merged 1 commit into from
Jul 29, 2026
Merged

feat: Support diff lang fences for HTML #208

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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
# intellij-markdown Changelog

## [Unreleased]
- Generate HTML with `code-line line-added`/`line-deleted` classes for added/deleted lines in `diff` / `patch` blocks
- Support tables inside list items
- Android compatibility issues

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28 changes: 23 additions & 5 deletions src/commonMain/kotlin/org/intellij/markdown/html/GeneratingProviders.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -197,18 +197,37 @@ internal class CodeFenceGeneratingProvider : GeneratingProvider {
}

var lastChildWasContent = false
var isDiff = false

val attributes = ArrayList<String>()
for (child in childrenToConsider) {
if (state == 1 && child.type in listOf(MarkdownTokenTypes.CODE_FENCE_CONTENT,
MarkdownTokenTypes.EOL)) {
visitor.consumeHtml(HtmlGenerator.trimIndents(HtmlGenerator.leafText(text, child, false), indentBefore))
val content = HtmlGenerator.trimIndents(HtmlGenerator.leafText(text, child, false), indentBefore)
if (isDiff && child.type == MarkdownTokenTypes.CODE_FENCE_CONTENT) {
val lineClass = when {
content.startsWith("+") -> "line-added"
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content.startsWith("-") -> "line-deleted"
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else -> null
}
if (lineClass != null) {
visitor.consumeTagOpen(child, "span", "class=\"code-line $lineClass\"")
visitor.consumeHtml(content)
visitor.consumeTagClose("span")
} else {
visitor.consumeHtml(content)
}
} else {
visitor.consumeHtml(content)
}
lastChildWasContent = child.type == MarkdownTokenTypes.CODE_FENCE_CONTENT
}
if (state == 0 && child.type == MarkdownTokenTypes.FENCE_LANG) {
attributes.add("class=\"language-${
HtmlGenerator.leafText(text, child).toString().trim().split(' ')[0]
}\"")
val info = HtmlGenerator.leafText(text, child).toString().trim()
val whitespaceIndex = info.indexOfFirst { it.isWhitespace() }
val language = if (whitespaceIndex == -1) info else info.substring(0, whitespaceIndex)
isDiff = language == "diff" || language == "patch"
attributes.add("class=\"language-$language\"")
}
if (state == 0 && child.type == MarkdownTokenTypes.EOL) {
visitor.consumeTagOpen(node, "code", *attributes.toTypedArray())
Expand Down Expand Up @@ -323,4 +342,3 @@ open class ImageGeneratingProvider(linkMap: LinkMap, baseURI: URI?) : LinkGenera
val REGEX = Regex("[^a-zA-Z0-9 ]")
}
}

5 changes: 5 additions & 0 deletions src/fileBasedTest/kotlin/org/intellij/markdown/HtmlGeneratorCommonTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,11 @@ class HtmlGeneratorCommonTest : HtmlGeneratorTestBase() {
defaultTest()
}

@Test
fun testDiffCodeFences() {
defaultTest()
}

@Test
fun testEscaping() {
defaultTest()
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32 changes: 32 additions & 0 deletions src/fileBasedTest/resources/data/html/diffCodeFences.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,32 @@
```diff
+added line 1
+added line 2
+added line 3
```

```diff metadata
+tab-separated info string
```

```diff
-removed line 1
-removed line 2
-removed line 3
```

```diff
context line
+added line 1
+added line 2
-removed line 1
-removed line 2
context line
```

```diff
+ <tag>&
-
+
plain line

```
44 changes: 44 additions & 0 deletions src/fileBasedTest/resources/data/html/diffCodeFences.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
<body>
<pre><code class="language-diff">
<span class="code-line line-added">+added line 1</span>

<span class="code-line line-added">+added line 2</span>

<span class="code-line line-added">+added line 3</span>

</code></pre>
<pre><code class="language-diff">
<span class="code-line line-added">+tab-separated info string</span>

</code></pre>
<pre><code class="language-diff">
<span class="code-line line-deleted">-removed line 1</span>

<span class="code-line line-deleted">-removed line 2</span>

<span class="code-line line-deleted">-removed line 3</span>

</code></pre>
<pre><code class="language-diff">
context line
<span class="code-line line-added">+added line 1</span>

<span class="code-line line-added">+added line 2</span>

<span class="code-line line-deleted">-removed line 1</span>

<span class="code-line line-deleted">-removed line 2</span>

context line
</code></pre>
<pre><code class="language-diff">
<span class="code-line line-added">+ &lt;tag&gt;&amp;</span>

<span class="code-line line-deleted">-</span>

<span class="code-line line-added">+</span>

plain line

</code></pre>
</body>
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